A Sunrise Medical White Paper 7477 E. Dry Creek Parkway Longmont, CO 80503 www.sunrisemedical.com JAY J3 Cushion: Design Improvements for Enhanced Clinical Benefit By: JAY Design Team 5/7/2009
Contents Introduction 2 Problem Statement 2 Previous Options 3 J3 Solution 3 Summary 5 Introduction A major physiological complication arising following SCI is the development of pressure sores due to tissue breakdown and cell necrosis. The development of pressure sores is known to be a multi-factorial process. Extrinsic factors relate to the physical conditions at the subject/support interface and affect soft tissue biomechanics. These must be considered in conjunction with intrinsic factors concerning the health and physiological profile of the individual. The baseline prevalence of pressure ulcer formation is believed to be approximately 30%. Incidence rates vary by level of spinal cord injury, race, sex and socio-economic factors. Most literature cites prevalence of pressure sore development in patients with quadriplegia to be as high as 60%. Though the morbidity rates due to a pressure ulcer have significantly improved over the past decade, recent studies still site an average of 7% loss of life due to complications of a pressure sore. Additionally, the medical costs associated with treatment range from $50,000 to $100,000 depending on the level of ulceration. The significance of this medical complication has long been the focus of the Jay seating design team. Over the past 3 years, this team has worked with leading industry experts to develop a better understanding of the role of material science along with cutting edge clinical theory and how it can be applied to advance the design of wheelchair cushions. This paper will discuss the design and development of the Jay 3 cushion in conjunction with a methodology termed Science of Seating. Clinical trial data will also be discussed to provide a baseline of connection between laboratory testing and clinical outcomes. Problem Statement The design challenge for the Jay team was to develop a cushion that would result in equivalent to superior pressure redistribution as compared to the Jay 2 deep contour, while improving secondary consumer requirements, such as comfort. 2
While reduction of pressure in a seated position is the primary design goal of a skin protection product, there are several additional factors that must be considered. Stability, transfer ease, heat and moisture management, positioning, and maintenance burden were also deemed important characteristics contributing to the overall success of the equipment in the daily life of a patient. As is the case with most design activities, the Jay team also wanted to improve the process of establishing the right fit for the patient. It was clear that even great concept could lead to a less than desirable clinical outcome if applied incorrectly. Previous Options The Jay 2 cushion platform has maintained great market acceptance due to a history of successful clinical outcomes. This cushion, launched in 1994 and was based on the concept of pressure reduction through the use of Hydrostatic Forces. Hydrostatic force is a force that is in balance or equally distributed such as when an object is immersed into a liquid or a gas. A hydrostatic force, when applied to a skin protection cushion, aids in evenly distributing the load to reduce pressure buildups under sensitive areas of the pelvis. The patented Jay fluid pad leverages this principal using a special high viscosity fluid that evens the load without compromising stability. Anyone who has tried to stand on a water bed quickly realizes the danger of using a low viscosity fluid. Need to introduce the concept of pelvic loading area before discussing Previously, the fitting of the pelvis to this Pelvic Loading Area or PLA was determined by the size of the cushion. As with many cushions on the market today, as the cushion grew in width, so did the PLA size. The complication with this approach is that a patient with a smaller pelvis size but a larger seated width could be continuously floating the entire pelvis in the PLA versus loading the trochanters. While this practice of floating the pelvis is at times intentional, such as when the trochanters are unable to bear an excessive load, the Jay team ascertained that the relationship of PLA to seat width was leading to an overuse of this technique of floating the pelvis. While not at the forefront of skin protection, achieving seated stability is critical to optimizing the functional independence of a patient in a wheelchair. Appropriate stability can mean the difference between safe reaching, the degree of lateral trunk support, ability to remain in a desired seated position and success in MRADL tasks such as adaptive driving. The base of the Jay 2 and J2 Deep Contour cushions is designed to create a superior degree of stability, particularly in the side to side direction; however, an overly large PLA, or a cushion absent a solid contoured base such as a complete air solution, could detract from an optimal outcome by limiting stability. As with many medical devices, multi-faceted goals can be difficult to achieve. Goals such as leg positioning and transfer ease often become secondary to optimal skin protection. The Jay 2 cushion was able to demonstrate that a cushion could both combine hydrostatic forces for optimal clinical outcome, while still providing a patient the option to position their legs. J3 Solution The goal of the Jay 3 cushion is to establish a new paradigm in PLA sizing so greater numbers of patients can achieve pressure redistribution and trochanter loading. The delivery of this technology has to ensure a good fit to the prescription method employed by today s rehab specialists, meaning that it has to be scalable across knowledge and process variations that may exist in the market place. Secondary goals are to extend the success of fluid immersion or hydrostatic loading by coupling it with segmentation or compartmentation of fluid that allows immersion without migration, which may lead to a negative outcome such as bottoming out. Benefit 1: PLA sizing independent of cushion width After a detailed study of anthropometrical data, it was determined that the average variation of pelvic width is less than 2 inches across 90% of adults. This finding lead the Jay team to decouple PLA sizing from cushion width, which may vary up to 10 in an average adult. The development of a PLA ring allows the clinician or ATP to accurately fit the patient to the PLA. 3
Utilizing a common measurement of ASIS width, clinician s and ATPs can match the trochanteric width, which closely parallels the ASIS width, to determine the correct PLA size. When the technique of floating the pelvis is required, a clinician can opt for the larger PLA size if available. Results: Invacare Infinity Lo Contour AirFlo Extreme Indenter Benchmarking Benefit 2: Enhanced immersion and envelopment leads to improved clinical outcomes As previously established, hydrostatic forces lead to lower overall pressures on sensitive areas by allowing these areas to immerse in a fluid medium. This immersion can be limited if the surface tension of the fluid container does not provide adequate fluid displacement. On the other hand, if the container does not limit the scope of fluid migration in key areas, such as the ischial tuberosities, there is a potential risk of losing fluid support altogether. The key is to provide room for displacement without fluid migration from a designated area. The new J3 Cushion design solution addresses both of these concerns. It is based upon 3 key elements: 1.) a pleating geometry that expands surface area when loaded, 2.) segmentation that prevents migration of fluid out of a specified area, and 3.) proper fluid fill levels by using independent supplement fluid pads to field verify the correct load. These benefits can be seen in the following laboratory and clinical trials, both performed by Sunrise Medical. Veralite Evolution Wave CPW Motion Concepts Matrx Flo-Tech Deep height benchmarks were Roho High Profile, Roho Quadra Select and the Jay 2 Deep Contour cushions. Results: Jay J2 J3 standard depth Right Ischial Tuberosity Left Ischial Tuberosity Right Trochanter Left Trochanter 0 50 100 150 200 250 300 Deep Depth Extreme Indenter Benchmarking Laboratory Testing: Methods: Laboratory testing consists of utilizing an extreme indenter, defined as an atrophied quad, as well as an anatomical representation of the pelvis consisting of a pelvic model embedded in a gelatinous material the shape of buttocks. The Jay 3 design was benchmarked using 2 versions: standard height and deep contour height. Standard height benchmarks were Jay J2, Motion Concepts Matrix Flo-Tech, Invacare Infinity Lo Contour AirFlo and the Varilite Evolution Wave. Jay 2 Deep Contour Roho Quadtro Select Roho High Profile Jay 3 Deep Contour Right Ischial Tuberosity Left Ischial Tuberosity Right Trochanter Left Trochanter 0 20 40 60 80 100 120 4
Clinical Testing: Both testing methods demonstrate a clear superiority of the Jay 3 design over the Jay 2 deep contour and an equivalency to the High Profile ROHO cushion as pertains to pressure management. Summary Based on the laboratory testing, the design of the standard J3 Cushion and the deep J3 Cushion proved superior in their ability to reduce peak pelvic pressures. 112763 Rev. A 5